Websailor's Wacky Wildlife World
Created | Updated May 7, 2008
A quirky look at wildlife. To be taken with a pinch of
salt, but with more than a grain of truth!
Seahorses on the Brain
During my formative years and later, I had this idea that seahorses were mythical creatures which didn't really exist. Even when I saw them on television they seemed ethereal and mysterious. So it is hardly surprising that when I saw them for real in our local sea life centre I was captivated.
Recently, I was delighted to learn that about five short-snouted seahorses (Hippocampus hippocampus) had been sighted in the river Thames, testament to the improving cleanliness of the river. It is unlikely they will venture far up the Thames as they cannot survive in freshwater, but it is believed they may have established a population there, and they are thought to be breeding on the south coast, too.
The two main species known to live around the British Isles are the aforementioned Short-snouted seahorse and the Spiny seahorse (Hippocampus guttulatus). The long- snouted seahorse (Hippocampus reidi) is also protected, along with some other species. They are generally found in our seas in the warmer months but, of course, this could be affected by climate change, as more strange creatures appear in our waters for the first time.
The news had been kept under wraps because at the time there was no legal protection in the UK. However, from the 14 April, 2008, around Britain seahorses and their environment will have protection under the Wildlife and Countryside Act 1981. They are listed as vulnerable, and any disturbance to their habitat could be catastrophic.
Having become fascinated by these strange fish, you could say I have seahorses on the brain, but in fact there is an odd connection between these creatures and our brains of which you may not be aware. In our brains, just behind the ears, is a set of seahorse-shaped neurons called, naturally enough, the hippocampus.
It is believed that this is where our short-term memories are translated into long-term memory. Loss of, or damage to this part of the brain can destroy a person's ability to absorb new memories, so that happenings of a few moments ago are promptly forgotten. So my research quite accidentally uncovered some sad but interesting facts, and though not strictly relevant to this article I wanted to share them.
Hippocampus means 'horse sea monster' and there are at least 33 known species, some twenty being threatened by trade in live and dried specimens, so those found in the Thames and round the south coast are doubly precious.
Their bodies are encased in a hard bony armour (no scales) and they use their dorsal fin for swimming which probably accounts for their very odd upright stance in the water. They live mainly on small crustaceans and fish fry (young fish) and have the delightful ability (like Chameleons) to change colour to match their surroundings. When I watch them, I am reminded of how, as children, we used to play horses using a house broom covered with an old sock. You will have to be of a certain age to remember that!
They come in sizes from 16mm (Pygmy seahorse: Hippocampus denise) up to 35cm in length (Hippocampus abdominalis) and are found around the world in tropical and temperate marine waters. Any larger, and they would certainly live up to their name. They live among sea grasses, mangroves and corals in coastal areas mainly in the West Atlantic or the Indo-Pacific region. Most live in shallow seas, some in deep water, and others are pelagic (living on the surface of the open seas).
One of the most fascinating facts about them is that the males incubate the eggs within a brood pouch, fertilising them after the females have deposited the eggs inside. Yes, the males. Now that I like! Watching them eject the eggs is quite amusing, but seeing them grow, for most of us, can only be observed in captivity.
Hundreds of mini seahorses are ejected at each contraction, but like so many species with huge broods, a comparatively small number survive. Their courtship dance is also something to behold, a kind of synchronised swimming; and they mate for life.
Dried seahorses are used in traditional Chinese medicine, being ground up as 'cures' for incontinence, impotence, heart disease and many other afflictions. They are also sold in large quantities in local markets as curiosa for tourists, and are exported to Taiwan, Japan, North America and Europe. Sadly, some very weird seahorse souvenirs can be found on the internet.
Live specimens are notoriously difficult to keep in captivity, and of the thousands caught every year for the aquarium trade large numbers die in transit, from a bad diet or from being kept in poor conditions.
Like so many conservation issues there are two sides to every story, but in the end the preservation of the species has to take precedence. Seahorses are threatened, and the fact that many fishing communities rely on the trade as a valuable source of income complicates matters. They are often the first to become aware of declining populations but perhaps are at a loss to put things right. Working with them is one possible answer. Brazil was one country involved in the dried seahorse trade and was a major exporter of live seahorses from as early as 1999. The principal species caught there, and popular with the aquarium trade is the long-snouted seahorse.
Whilst such species were caught for local consumption, the catch was sustainable, but once the other demands on the species increased, numbers plummeted. Strangely, they are one of the few fish not caught for food, in which trade has been monitored. Therefore we know that as far back as 2002 trade amounted to 70 tons - about twenty four and a half million of these harmless creatures! At one time some 32 countries traded in seahorses, but more recent research has shown that at least 77 countries are now involved.
As a consequence, 32 species are listed on the IUCN Red List, and the entire genus is included in Appendix II of the Convention on International Trade in Endangered Species (CITES).
Important seahorse habitats, such as reefs and mangroves, are being damaged and destroyed world-wide. These fish do not travel far and tend to stick to algae, sea grasses, rocks, coral, and roots of mangrove trees, relying on camouflage to protect them from natural predators. However, there are other important reasons why such habitats should be protected.
No-one is likely to forget the Boxing Day Tsunami of 2004 when huge waves swept away all before them throughout much of south and east Asia. This would once have been ideal seahorse habitat. Afterwards, conservationists were adamant that the destruction would not have been nearly so dire if beaches had not been cleared of mangroves and other vegetation to make way for hotels and tourist beaches.
It was proven to be the case in two villages in Sri Lanka, where just two people died, where there was dense mangrove and scrub forest, yet about 6,000 died where there was no such protection. Moves are afoot to regenerate mangrove forests, but of course it will no longer be possible in some areas.
Nature provides us with some truly unique spectacles on land, in the air and in the sea, but I think the seahorse has to be one of the strangest, yet most captivating of all.
At the beginning of the holiday season: please don't be tempted to buy them as souvenirs. Hopefully your own hippocampus will have stored this information in your long-term memory and you won't be tempted by such things.
However, should you decide you want to keep live ones in captivity, please, please make sure that you have all the necessary information and equipment and that you buy from a reputable source. I am sure they will provide hours of entertainment but in all honesty shouldn't they be left where they belong - in our coastal waters?
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